The present disclosure relates to a pyroelectric type infrared sensing element in which intrinsic polarization is changed by radiation of an infrared ray to generate surface electric charges, and an infrared imaging device using the same.
Sensors for sensing infrared rays are roughly classified into two kinds of sensors called a quantum type infrared sensing element and a heated type infrared sensing element in terms of the operating principles. In particular, the heated type infrared sensing element in which an incident infrared ray is absorbed to change a temperature of a light receiving element, thereby sensing the infrared ray has an advantage such that cooling is unnecessary. For this reason, in recent years, the heated type infrared sensing element has been utilized as an imager of an infrared imaging device (thermography), or a human-sensor with which an eco product or the like is loaded.
It is known that the heated type infrared sensing elements, for example, are classified into the following three kinds of infrared sensing elements. One of them is a thermopile type infrared sensing element to which a thermocouple for causing the Seebeck effect is connected. Another one of them is a bolometer type infrared sensing element which utilizes a change in resistance value due to temperature rise. Also, there is known a pyroelectric type infrared sensing element which generates surface electric charges due to a change in intrinsic polarization of a pyroelectric element.
In the pyroelectric type infrared sensing element, a research for devising the kinds and compositions of the pyroelectric materials, thereby enhancing a pyroelectric coefficient as an efficiency of generation of the surface electric charges due to a temperature change, and a research for efficiently absorbing an incident infrared ray are carried out for the purpose of enhancing the sensitivity for the infrared ray. For example, an infrared sensing portion using a pyroelectric effect thin film is described as an infrared temperature sensor for measuring a temperature in a non-contact style in Japanese Patent Laid-Open No. 2006-349601 (hereinafter referred to as Patent Document 1). Also, a construction is proposed in which a member for shielding an infrared ray is arranged so as to face the infrared sensing portion, and a minute window is provided in the shielding member, thereby making it possible to measure a temperature of a minute area.